Re: [PATCH v2] Bluetooth: Retry configure request if result is L2CAP_CONF_UNKNOWN

On Tue, May 21, 2019 at 6:31 PM Andrey Smirnov [off-list ref] wrote:

Due to:

 * Current implementation of l2cap_config_rsp() dropping BT
   connection if sender of configuration response replied with unknown
   option failure (Result=0x0003/L2CAP_CONF_UNKNOWN)

 * Current implementation of l2cap_build_conf_req() adding
   L2CAP_CONF_RFC(0x04) option to initial configure request sent by
   the Linux host.

devices that do no recongninze L2CAP_CONF_RFC, such as Xbox One S
controllers, will get stuck in endless connect -> configure ->
disconnect loop, never connect and be generaly unusable.

To avoid this problem add code to do the following:

 1. Parse the body of response L2CAP_CONF_UNKNOWN and, in case of
    unsupported option being RFC, clear L2CAP_FEAT_ERTM and
    L2CAP_FEAT_STREAMING from connection's feature mask (in order to
    prevent RFC option from being added going forward)

 2. Retry configuration step the same way it's done for
    L2CAP_CONF_UNACCEPT

Signed-off-by: Andrey Smirnov <redacted>
Cc: Pierre-Loup A. Griffais <redacted>
Cc: Florian Dollinger <redacted>
Cc: Marcel Holtmann <marcel@holtmann.org>
Cc: Johan Hedberg <redacted>
Cc: linux-bluetooth@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
---

Changes since [v1]:

   - Patch simplified to simply clear L2CAP_FEAT_ERTM |
     L2CAP_FEAT_STREAMING from feat_mask when device flags RFC options
     as unknown

[v1] lore.kernel.org/r/20190208025828.30901-1-andrew.smirnov@gmail.com

Pinging the status of this. Marcel, do you have any feedback on v2?

Thanks,
Andrey Smirnov